During the processing of photographic materials, one or more rinsing or washing steps may be used to remove residual processing solution from the materials prior to contact with the next processing solution. Moreover, before processed materials are dried, they are generally washed a last time to remove all remaining chemical residues so that when they are dried, they are free of lines, water spots or scum. For example, in processing most films and papers (both color and black and white), a final rinsing or stabilizing step is used prior to drying.
Many different formulations have been proposed for use as final rinse solutions in photographic processes immediately prior to drying. Generally, they include one or more surfactants that facilitate the "cleaning" of the photographic material and uniform liquid drainage. In addition, rinse solutions can contain one or more biocides to prevent unwanted biological growth in the processing tank or on the photographic material. The solutions may additionally contain calcium ion sequestering agents or polymers such as polyvinylpyrrolidone to reduce precipitation of sulfur or sulfides.
To meet all of the needs of a final rinse solution, a careful formulation of components, generally surfactants and biocides, must be made. Proper balancing is required to keep costs low, minimize foaming and biological growth, while achieving the desired drainage and defect free processing expected by highly critical customers.
Not every final rinse solution useful for processing one type of photographic element may be useful for processing other types of elements. Each type of photographic element may have surface characteristics, or be processed using unique chemicals that require unique final processing solution components. In addition, not every final rinse solution can be successfully used with any type of processing equipment and arrangement.
A conventional final rinse solution useful for processing color motion picture films includes a single nonionic surfactant, such as tridecylpolyethyleneoxide(12) alcohol.
A commercial final rinse solution used to process color negative films is also known to include a nonionic fluorosurfactant in combination with a nonionic nonfluorinated surfactant, and a conventional biocide. This solution acceptably cleans photographic films in roller transport processing machines. However, when it is used to process films in what are known as "rack and tank" processors, it fails to clean acceptably, and leaves what are known as "drying lines" and other defects on the processed films. This problem is particularly evident when films having magnetic backing layers are processed in such processors. Rack and tank processors are designed without squeegees that are present in other types of processors to remove solution from the processed films. Thus, rack and tank processors are the "worst case" processors for any final rinse solution, and if a solution cleans acceptably in rack and tank processors without scum and drying lines on the films, it will likely clean well in any other type of processor.
Thus, there is a continuing need in the art for an improved, low cost, highly effective, final rinse solutions that achieves all of the desired results when various films, especially magnetic layer-backed films, are processed in various processing machines, including rack and tank processors.